The known machines for the manufacture of continuous mesh bags are made up of tubular mesh feed devices and a first and second laminate of thermally weldable material and opening means of the tubular mesh, which comprise an expanding core arranged floating and vertically inside the tubular mesh and are supported by at least one pair of rotating rollers outside the mesh, the shafts of which are integral to the machine.
The machines also have one or several traction devices, made up, for example, of pairs of rollers which rotate in the opposite direction and between which the tubular mesh is forced to circulate in an upward or downward direction on the outside of the expanding core. Some machines are also provided with welding devices, in order to weld the laminates of thermally weldable material onto the tubular mesh as it passes through said expanding core and with devices for cutting the tubular mesh and closing the section which has been cut at the bottom, in order to thus make up a bag bottom.
The laminates of thermally weldable material are used to join the bag ends and make up the bottom thereof, as well as to close the bag after the filling thereof. In addition, the laminates are used to print the identifying data of the bag, its content or for advertising.
However, when the mesh is stretched by the traction devices, it frequently undergoes some kind of deformation, and that one of its faces, and the corresponding laminate of thermally weldable material, is displaced as regards the other face and corresponding laminate. In the event of there being equal or complementary information on the laminates adjoining the two faces of the tubular mesh, this effect leads to said information not matching when the tubular mesh and adjoining laminates are cut and then welded to make up the bag bottom or the subsequent closing thereof.
Progressively, and as the machine drags the tubular mesh in order to manufacture one bag after the other, this small difference in displacement between the laminates increases, in such a way that it is necessary to stop the machine in order to manually align the two laminates to be affixed to the two sides of the same bag.
In the event of the laminates having different colour printing for the bottom or the upper fastener, or should the laminates incorporate signs to be detected by optical readers and activate some sort of device on the machine, the non-alignment of the laminates can cause serious consequences, forcing the bag production to be stopped, as well as the filling and closing thereof, since the bags that are manufactured may be faulty.
Therefore, the need for a machine which allows for the continuous manufacture of mesh bags, which ensures the alignment of the adjoining laminates to the faces of the tubular mesh and which are an improvement on the current drag systems for mesh bags along a core expander is noted.